Are you over 40 and getting forgetful? Having trouble learning new tricks? Here neurobiologist Lawrence Katz and self-help author Manning Rubin introduce a unique brain exercise program that they call "Neurobics"—a deceptively simple and entertaining series of 83 activities intended to stimulate the production of brain cells. When you exercise the brain, you release natural growth factors called neurotrophins, which in turn enhance the brain's level of fitness. Neurobics uses the five senses in unexpected ways to shake up your everyday mental routines; if you're right-handed, for example, brush your teeth tomorrow morning with your left hand. Or close your eyes before you get into the car and then get the key into the ignition. Each new activity opens a new neural pathway in your brain.